Means of increasing stall torque of piston-type radial air motors



June 13, 1967 1. MAN$ELL 3,324,759

MEANS OF INCREASING STALL TORQUE OF PISTON-TYPE RADIAL AIR MOTORS Filed Feb. 12, 1965 5 Sheets-Sheet 1 INVENTOR W01? MA IVSEZ. L

QM w Ti/LW ATTORNEY June 13, E96? 1. MANsELL 3,324,759

MEANS OF INCREASING STALL TORQUE OF PISTON-TYPE RADIAL AIR MOTORS Filed Feb. 12, 1965 s Sheets-Sheet 2 W 293 77 1.0.6. m m )x r m LARGE mm; Pam: m w I b )3 F. 4 \\\(0PE\E M SMALL Wm? FUR? PASSAGE "was! INVENIO%. 1/5/05? IMfl/VSELL i9 Mm w. Twfimp ATTD RN E Y June 13, 195: MANSELL 3324J MEANS OF INCREASING STALL TORQUE OF PISTON--TYPE RADIAL- AIR MOTORS Filed Feb. 12, 1965 CF??? ASE GONSUWW'E QUN JORQUE (5-53%?) RPM INVENTOR. I M99? iE M/V3l A United States PatentO 3,324,769 MEANS OF INCREASING STALL TQRQUE F PISTQN-TYPE RADIAL AIR MOTORS Ivor Mansell, Chateauguay, Quebec, Canada, assignor to Canadian Ingersoli-Rand Company Limited, Montreal,

Quebec, Canada, a corporation of Canada Filed Feb. 12, 1965, Ser. No. 432,147 16 Claims. (Cl. 91-12) This invention relates to piston-type finid motors and has particular reference to the provision of new and improved means for increasing the stall torque of a pistontype radial air motor.

In a piston-type radial air motor, the air distributor valve is commonly constructed to cut off the compressed air supplied to each of the motor pistons at a crankshaft angle approximately ninety degrees after the piston passes its Top Dead Center position. This timing has been found to be a desirable compromise for normal and high speed performance; that is, maximum piston output energy for minimum air input energy.

During stall and slow speed motor operation, maximum motor performance is obtained when the compressed air is supplied to the pistons continuously throughout their power strokes. This continuous supplying of air is, of course, undesirable and inefiicient during normal and high .speed motor operation and is desirable only during stall and slow speed motor operation.

Thus, a retardation of the cutting off of the compressed air to the motor pistons during only stall and slow speed motor operation will provide a greater stall torque and will enhance motor performance.

It has been suggested that this retardation of the air out off point during slow and stall speed motor operation be effected through the use of an advance and retard mechanism. Such a mechanism is believed to be undesirable for this purpose, however, due to its relative complexity and expensiveness.

An object of the present invention is to provide new and improved valving means for increasing the stall torque of a piston-type radial air motor.

Another object of the invention is to provide new and improved valving means of the type set forth which produces no significant effect upon other than stall and slow speed motor performance.

Another object is to provide new and improved valving means of the type set forth which provides an increased motor stall torque without requiring a corresponding increase in motor air consumption at normal and high speeds.

Another object is to provide new and improved valving means of the type set forth which increases the overall operating performance of the air motor.

Another object is to provide new and improved valving means of the type set forth which is relatively simple and economical in construction while being eflicient and simple in operation.

Other objects and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings. It will be understood that changes may be made in the details of construction and arrangement of parts shown and described as the preferred forms of the invention have been given by way Patented June 13, 1967 FIG. 3 is an enlarged sectional view taken on line 33 of FIG. 1 looking in the direction of the arrows;

FIG. 4 is a schematic view of the valving means of the present invention relative to crank angle;

FIGS. 5 through 7 are enlarged, fragmentary, sectional views illustrating the relationship between the valving means of the present invention and one of the motor pistons during three different crank angles;

FIG. 8 is a graphical representation of the torque and air consumption curves of the present invention as compared to those of conventional motors; and

FIG. 9 is an enlarged sectional view of an alternative form of the present invention.

Although the present invention has been illustrated, and will be hereinafter described, with reference to a pistontype radial air motor of the four-cylinder type, it will be understood that such has been done for the purposes of illustration only.

Referring more particularly to the drawings wherein similar reference characters designate corresponding parts throughout the several views, FIGS. 1 through 3 illustrate a pistontype radial air motor which is designated generally at 10. The motor 10 is supported within a housing which includes a base portion 14 and a motor carrying portion 16 which is supported by the base portion 14. The motor carrying portion 16 of the housing is provided with the usual vent means 18 which are adapted to vent the interior of the housing.

As illustrated, the air motor 10 is of the four-cylinder type and includes the four cylinders 20 which are radially carried by the motor carrying portion 16 of the housing. The motor pistons 22 correspond in number and in disposition to the cylinders 29 and are operatively disposed therein. Each of the pistons 22 is joined by a connecting rod 24 to a crank 26 which is operatively associated with the longitudinally disposed, rotatably supported shaft 28. The shaft 28, as will be seen from FIG. 1, includes a reduced plain end portion 30 which extends externally of the housing and is adapted for connection to a driven apparatus such as a hoist or the like (not shown).

The motor carrying portion 16 of the housing is pro vided with a lon itudinally extending bushing 31 having a longitudinally extending bore 32 and includes a fluid inlet port 34 which communicates the bore 32 through the fluid hose 36 with a source of compressed air (not shown). The motor carrying portion 16 of the housing also includes a fluid exhaust port 33 which communicates with the bore 32 at an end thereof and the fluid passage means 40 which communicate the opposite end of the bore 32 with each of the cylinders 20.

A valve member 42 is longitudinally disposed within the bore 32 and is secured by the key means 44 to the rotatably mounted shaft 28 for rotation therewith. The valve member 42 includes an inlet fluid passage 46 which has an end communicating with the inlet port 34 through the circumferentially disposed fluid passage means 48 continuously throughout the rotation of the valve member 42. The opposite end of the inlet fluid passage 46 is adapted to selectively deliver compressed air to each of the cylinders 20 successively during the intake stroke of the pistons 22 and communicates selectively during the rotation of the valve member 42 through a port 50 with the ports 51 in the bushing 31 communicating with each of the fluid passage means 4t). The port 59 is disposed Within the valve member 42 and, as illustrated, is adapted to operatively communicate with each of the fluid passage means 41} throughout ninety degrees of crankshaft angle.

The valve member 42 further includes a fluid exhaust passage 52 which extends substantially throughout the length thereof. The exhaust passage 52 has an end in continuous communication with the exhaust port 38 in the 3 housing throughout the rotation of the valve member 42. The opposite end of the exhaust passage 52 is adapted to selectively receive exhaust air through the port 54 in the valve member 42 from the cylinders 20 successively being exhausted during the rotation of the valve member 42.

The present invention comprises, generally, the provision of new and improved means within the valve member 42 for supplying compressed air to the cylinders 20 after the port 50 in the valve member 42 has rotated out of communication with the passage means 40 communicating therewith but prior to the exhausting of the cylinders 20.

More specifically, a small diameter, elongated fluid passage 56 is formed within the end of the valve member 42 communicating with the fluid passages 40. The fluid passage 56 communicates the inlet fluid passage 46 with a port 58 on the circumference of the valve member 42 between the cut-off edge of the port 50 and the leading edge of the exhaust port 54. The fluid passage 56 is adapted to supply a metered amount of compressed air to each of the cylinders 20 after the cut off of the compressed air from the port 50 to prevent expansion of the compressed air in the cylinders 20 and to provide additional motive force for urging the pistons 22 towards Bottom Dead Center.

As the fluid passage 56 is of elongated, small diameter construction, it readily accomplishes this object during stall and slow speed operation of the motor 10. However, due to this elongated, small diameter construction, the flow of compressed air through the fluid passage 56 produces no significant effect upon normal and high speed operation of the motor and results in no significant increase in air consumption.

In the illustrated embodiment of the invention wherein the port 50 is adapted to supply compressed air to the cylinders during ninety degrees of crank angle, the port 58 illustrated is disposed on the outside diameter of the valve member 42 forty degrees after the cut-oft" edge of the port 50. Due to this angular placement of the passage means 56, it will be seen that no time lag occurs between the cut off of the air flow through the port 50 and the commencing of the air flow from the passage means 56. Thus, the flow of compressed air into each of the cylinders 20 is continuous until the piston 22 therein approaches its Bottom Dead Center position.

By way of specific example, it has been determined that within a motor 10 constructed in accordance with the disclosed embodiment of the invention and having a line air pressure of ninety pounds per square inch gauge, a passage means 56 of a diameter of less than one-eighth inch will increase the Mean Efiective pressure in the cylinders 20 up to line pressure below ten r.p.m. This increase in air pressure has been found to result in an increase in motor stall torque of approximately ten percent while requiring an increase in air consumption of only around five cubic feet per minute.

FIG. 4 illustrates, schematically, the relationship between the operation of the illustrated valve member 42 and the crank angle.

As shown therein, with one of the pistons 22 at Top Dead Center, the port 50 in the valve member 42 opens and directs compressed air into the cylinder 20 containing the piston 22. The port 50 remains open throughout the first ninety degrees of crank angle and then is cut off from the cylinder 22 by the rotation of the valve member 42. At this ninety degree crank angle, the passage 56 in the valve member 42 opens and directs a metered amount of compressed air into the cylinder 20 throughout the following forty degrees of crank angle. Due to the provision of passage 56, thus, the flow of compressed air to the cylinder 20 is effectively continued throughout one hundred and thirty degrees of crank angle and is not cut off after ninety degrees thereof as is conventional.

FIGS. 5 through 7 illustrate the relative positioning of the valve member 42 and a piston 22 during the crank angles schematically illustrated in FIG. 4.

As illustrated in FIG. 5, with the crank angle at zero degrees, the piston 22 is at Top Dead Center and the port 50 in the valve member 42 enters operative communication with the fluid passage 40 leading to the cylinder 20.

The flow of compressed air from the port means 50 to the passage means 40 continues throughout ninety degrees of crank angle until the valve member 42 rotates the port 50 out of operative communication with the cylinder 20 as is illustrated in FIG. 6. At this time, the passage 56 in the valve member 42 enters into communi eating relationship with the passage means 40 and directs a metered amount of compressed air thereinto.

The passage 56 remains in communication with the passage means 40 throughout the next forty degrees of crank angle until the position of FIG. 7 is attained. Then, with the piston 22 approaching Bottom Dead Center, the flow of air from the passage 56 to the passage means 40 is cut off. Exhausting of the cylinder 20 is accomplished in a conventional manner by the exhaust passage 52 in the valve member 42.

FIG. 8 illustrates the torque and air consumption curves of the present invention in dotted lines as compared to those of a conventional piston-type radial air motor in solid lines and shows that the present invention provides greatly enhanced stall torque in return for only slightly increased air consumption.

FIG. 9 illustrates an alternative embodiment of the invention wherein the passage means 56 includes a widened portion 60 and a ball valve 62 is mounted upon a spring or similar resilient member 64 within the widened portion 60. As illustrated, the valve member 42 includes a threaded, adjustable portion 66 which is mounted upon the shims 68, thus allowing adjustment of the ball valve 62.

In this embodiment of the invention, it will be seen that the flow of the compressed air through the passage means 56 is prevented until the pressure of the air overcomes the resisting force of the spring 64 and opens the ball valve 62.

The operation of the device is believed to be apparent from the foregoing.

From the foregoing, it will be seen that I have provided new and improved means for accomplishing all of the objects and advantages of the invention.

Having described my invention, I claim:

1. A piston-type radial air motor comprising:

(a) a rotatably mounted shaft;

(b) a plurality of cylinders radially disposed around said shaft;

(c) a piston within each of said cylinders for reciprocatory movement therein;

((1) crank means associated with said shaft and operatively connecting said pistons with said shaft; and

(e) rotary valve means connected to be rotated during rotation of said shaft and including inlet fluid passage means and exhaust fluid passage means, said rotary valve means having first port means selectively communicating each of said passage means succes sively with each of said cylinders during the rotation of said valve means;

(f) said rotary valve means further including third fluid passage means communicating said inlet fluid passage means with second port means formed in said valve means intermediate said first port means and adapted to supply pressurized fluid to said cylinders intermediate the communication of said first port means therewith.

2. A piston-type radial air motor according to claim 1 wherein said first port means comprises a first fluid port communicating said inlet fluid passage means with said cylinders and a second fluid port communicating said exhaust fluid passage means with said cylinders, said fluid ports being adapted to selectively supply and exhaust pressurized fluid from each of said cylinders, respectively, during the rotation of said valve means, and said second port means is intermediate the rearward edge of said first fluid port and the forward edge of said second fluid port.

3. A piston-type radial air motor according to claim 1 wherein valve means are provided in said third fluid passage means for controlling the flow of pressurized fluid therethrough.

4. A piston-type radial air motor comprising:

(a) a rotatably mounted shaft;

(b) a plurality of cylinders radially around said shaft;

(c) a piston within each of said cylinders for reciprocatory movement therein;

(d) crank means associated with said shaft and operatively connecting said pistons with said shaft; and

(e) rotatably operable valve means associated with said shaft for rotation therewith and including inlet fluid passage means and exhaust fluid passage means, said valve means having a plurality of fluid ports selectively communicating said passage means successively with each of said cylinders during the rotation of said valve means;

(if) said valve means including restricted fluid passage means communicating said inlet fluid passage means with port means on said valve means intermediate said fluid ports for supplying a metered amount of pressurized fluid to each of said cylinders intermediate the communication of said fluid ports therewith.

5. A piston-type radial air motor according to claim 4 wherein said restricted fluid passage means communicating said inlet fluid passage means with said port means comprises an elongated, narrow diameter bore in said valve means.

6. A piston-type radial air motor according to claim 4 wherein said port means in said valve means is between the trailing edge of the fluid port communicating said inlet fluid passage means with said cylinders and the leading edge of the fluid port communicating with said exhaust fluid passage means with said cylinders.

7. A piston-type radial air motor comprising:

(a) a rotatably mounted shaft;

(b) a plurality of cylinders radially about said shaft;

(c) a piston within each of said cylinders for reciprocatory movement therein;

(d) crank means associated with said shaft and connecting said pistons thereto for reciprocatory movement in said cylinders; and

(e) valve means operatively associated with said shaft for rotary movement therewith;

(if) said valve means including a first fluid passage for transmitting pressurized air to said cylinders and a second fluid passage for removing exhaust air from said cylinders;

(g) said first and second fluid passages, respectively, selectively communicating successively through first and second port means in said valve means with said cylinders during the rotation of said valve means;

(h) said valve means including a third fluid passage of elongated, narrow diameter configuration communicating said first fluid passage with third port means upon said valve means intermediate the trailing edge of said first port means and the leading edge of said second port means and supplying a metered amount of pressurized air to each of said cylinders after the cut off of said first fluid passage therefrom.

8. A piston-type radial air motor according to claim 6 wherein said first port means communicate with each of said cylinders during ninety degrees of crank angle and the third port means communicate with said cylinders during the succeeding forty degrees of crank angle.

9. A piston-type radial air motor according to claim 7 wherein said first port means communicate with each of said cylinders during the first ninety degrees of crank angle after the pistons pass Top Dead Center and said 6 third port means communicate with said cylinders during .the succeeding forty degrees of crank angle.

10. A piston-type radial air motor comprising:

(a) a housing;

(b) a shaft journalled for rotation in said housing;

(c) a plurality of cylinders radially around said shaft within said housing;

(d) a piston within each of said cylinders for reciprocatory movement therein;

(e) crank means within said housing and associated with said shaft operatively connecting said pistons with said shaft; and

(f) valve means in said housing and associated with said shaft for rotation therewith;

(g) said valve means including a first fluid passage adapted to selectively connect each of said cylinders with a source of pressurized air and a second fluid passage adapted to selectively exhaust air from said cylinders;

(h) said first and second fluid passages communicating with first and second port means, respectively, in said valve means;

(i) said housing including a plurality of fluid passages communicating each of said first and second port means selectively with each of said cylinders during the rotation of said valve means;

(j) said valve means including a narrow diameter,

elongated bore communicating said first fluid passage with a third port means formed in said valve means intermediate said first and second port means and supplying a metered amount of pressurized air to said cylinders intermediate the connections of said first and second port means therewith.

11. A piston-type radial air motor according to claim 10 wherein valve means are disposed in said narrow diameter, elongated bore and control the flow of pressurized air therethrough.

12. A piston-type radial air motor comprising:

(a) a rotatably mounted shaft;

(b) a plurality of cylinders radially around said shaft;

(c) a piston within each of said cylinders for reciprocatory movement therein;

(d) crank means associated with said shaft and operatively connecting said pistons with said shaft; and

(e) rotary valve means connected to be rotated during rotation of said shaft and including inlet fluid passage means and exhaust fluid passage means, said valve means having first port means for communicating said passage means successively with each of said cylinders during the rotation of said valve means;

(f) said valve means including third fluid passage means, communicating with second port means formed in said valve means intermediate said first port means, for supplying a metered quantity of pressurized fluid to said cylinders intermediate the communication of said first port means therewith.

13. A piston-type radial air motor according to claim 12 wherein said third fluid passage means comprises a restricted bore formed in said valve means.

14. A piston-type radial air motor according to claim 12 wherein said inlet fluid passage means and said third fluid passage means are arranged such that said inlet fluid passage means supplies pressurized fluid to each of said cylinders during approximately the first half of the power stroke of the respective piston disposed therein and said third fluid passage means supplies pressurized fluid to each of said cylinders during the last half of the power stroke of their respective pistons.

15. A piston-type radial air motor according to claim 12 wherein a valve is disposed in said third fluid passage means for controlling the flow of pressurized fluid therethrough.

16. A piston-type radial air motor according to claim 12 wherein said inlet fluid passage means communicates with each of said cylinders during the first ninety degrees of crank angle after the pistons pass Top Dead Center UNITED STATES PATENTS 2,052,472 8/1936 Hyman 91-180 2,184,678 12/1939 Mueller 137-62547 2,252,134 8/1941 Mueller 137-62547 Stuver 91-180 Wiedmann 91-180 Strickland 91-180 Racicot 91-180 Feaster 91-180 MARTIN P. SCHWADRON, Primary Examiner.

B. L. ADAMS, Assistant Examiner. 

1. A PISTON-TYPE RADIAL AIR MOTOR COMPRISING: (A) A ROTATABLY MOUNTED SHAFT; (B) A PLURALITY OF CYLINDERS RADIALLY DISPOSED AROUND SAID SHAFT; (C) A PISTON WITHIN EACH OF SAID CYLINDERS FOR RECIPROCATORY MOVEMENT THEREIN; (D) CRANK MEANS ASSOCIATED WITH SAID SHAFT AND OPERATIVELY CONNECTING SAID PISTONS WITH SAID SHAFT; AND (E) ROTARY VALVE MEANS CONNECTED TO BE ROTATED DURING ROTATION OF SAID SHAFT AND INCLUDING INLET FLUID PASSAGE MEANS AND EXHAUST FLUID PASSAGE MEANS, SAID ROTARY VALVE MEANS HAVING FIRST PORT MEANS SELECTIVELY 